5' RACE help

Hi there, I am trying to separate a short cDNA (50 bases) fragment from
the primer (23 nt), after the first strand cDNA synthesis. This has been
difficult since the primer and the cDNA are close in size and I need a
clean cDNA for the c-tailing reaction.
Any suggestions to get this cDNA clean from the primer are welcome. Recall
also that the amount of cDNA that I obtain is very LOW and I have not been
able to see it on acrylamide gels !!
Thanks,
N.A. Salazar, Ph.D.
nsalazar at u.washington.edu